91 accord ex O2 sensor location help???

I need to replace my oxygen sensor in my 91 accord EX, the problem is that I cant find it. It is not in the exhaust manifold where my manual says it should be (I removed the heat shield and checked). Thanks in advance for any help!

It is just before the cat converter to the rear of the engine. It is the only thing that has wires attached to the exhaust pipe.